What purpose would be served by developing AI's that experience human-like emotions?
The answer to this question, unlike many on this board, I think is definitive. No. We don't need AI's to have emotion to be useful, as we can see by the numerous amount of AI's we already have that are useful.

But to further address the question, we can't really give AI's emotions. I think the closest we can get would be 'Can we make this AI act in a way a human would if that human was insert emotion?'. I guess in a sense, that is having emotion, but that's a whole other discussion.

And to what end? The only immediate reason coming to mind would be to create more lifelike companions or interactions, for the purposes of video games or other entertainment. A fair goal, but far from necessary. Even considering an AI-imbued greeting robot in the lobby of some building, we'd probably only ever want it to act cordial.

Yann says that super-advanced AI would lead to more human-like qualities and flaws. I think it's more like it would 'give our AI's more human-like qualities or in other words flaws'. People have a tendency to act irrationally when sad or angry, and for the most part we only want rational AI. To err is human, as they say.

The purpose of AI's and learning algorithms is to create systems that act or 'think' like humans, but better. Systems that can adapt or evolve, while messing up as little as possible. Emotive AI has uses, but it's certainly not a prerequisite for a useful system.